# 使用解析Python工具 一次就上手_解開函式類別的奧秘 ###### tags: `python` Copyright 2021, [月下麒麟](https://hackmd.io/@YMont/note-catalog) --- ## Outline 當你應用Python一段時間後，常常會接觸到第三方套件，此時你可能就會將它下載下來做使用。那麼，人總會有好奇心，會想對這個source code(公開的自由軟體原始碼)做一番了解，如它的class, function...，但是程式碼這麼長，它們彼此間的關聯是什麼、又該如何追蹤起? 在探討上述問題前，先來思考一個情境: `假設它的類別(class)分類有10個，然後每個類別底下又各有10個函式(function)，看到這裡，心裡一想可能覺得這個數量還可以trace。假設我們再把數量乘於5倍呢? 試問，你還會想對這個程式進行追蹤嗎? 沒有一定的答案，但你一定會追蹤的很心煩!` ## tool installation * `pip install pylint` * download and install [Graphviz](https://graphviz.org/download/) * git clone open source code [netmiko](https://github.com/ktbyers/netmiko.git) * Document: [What is the netmiko?](https://pynet.twb-tech.com/blog/netmiko-python-library.html) ## tool guide **open CMD terminal** `pyreverse --help` ``` Usage: pyreverse [options] <packages> create UML diagrams for classes and modules in <packages> Options: -h, --help show this help message and exit -f <mode>, --filter-mode=<mode> filter attributes and functions according to <mode>. Correct modes are : ... ... ``` **command** `D:\temp>pyreverse -mn -a1 -s1 -f ALL -o pdf D:\netmiko\netmiko\cisco` ``` parsing D:\netmiko\netmiko\cisco\__init__.py... parsing D:\netmiko\netmiko\cisco\cisco_asa_ssh.py... parsing D:\netmiko\netmiko\cisco\cisco_ftd_ssh.py... parsing D:\netmiko\netmiko\cisco\cisco_ios.py... parsing D:\netmiko\netmiko\cisco\cisco_nxos_ssh.py... parsing D:\netmiko\netmiko\cisco\cisco_s300.py... parsing D:\netmiko\netmiko\cisco\cisco_tp_tcce.py... parsing D:\netmiko\netmiko\cisco\cisco_viptela.py... parsing D:\netmiko\netmiko\cisco\cisco_wlc_ssh.py... parsing D:\netmiko\netmiko\cisco\cisco_xr.py... parsing D:\netmiko\netmiko\cisco\__init__.py... ``` **get result** It will download two PDF files automatically. There are name =="classes.pdf"== and =="packages.pdf"== **program flow chart** ![](https://i.imgur.com/u8UuENQ.png) classes.pdf ![](https://i.imgur.com/02hGj1e.png) packages.pdf **check detail** ![](https://i.imgur.com/eVg05Ta.png) We reference source code. ```python= class CiscoIosBase(CiscoBaseConnection): """Common Methods for IOS (both SSH and telnet).""" def __init__(self, *args, **kwargs): # Cisco-IOS defaults to fast_cli=True and legacy_mode=False kwargs.setdefault("fast_cli", True) kwargs.setdefault("_legacy_mode", False) return super().__init__(*args, **kwargs) def session_preparation(self): """Prepare the session after the connection has been established.""" cmd = "terminal width 511" self.set_terminal_width(command=cmd, pattern=cmd) self.disable_paging() self.set_base_prompt() def check_config_mode(self, check_string=")#", pattern="#"): """ Checks if the device is in configuration mode or not. Cisco IOS devices abbreviate the prompt at 20 chars in config mode """ return super().check_config_mode(check_string=check_string, pattern=pattern) def save_config(self, cmd="write mem", confirm=False, confirm_response=""): """Saves Config Using Copy Run Start""" return super().save_config( cmd=cmd, confirm=confirm, confirm_response=confirm_response ) ``` Then, We can find the class name is 'CiscoIosBase' and get four function is '\_\_init\_\_', 'session_preparation', 'check_config_mode', 'save_config' Thanks for your reading. reference:[subprocess call unable to find dot although it's installed](https://stackoverflow.com/questions/66040824/subprocess-call-unable-to-find-dot-although-its-installed) reference:[Converting dot to png in python](https://stackoverflow.com/questions/5316206/converting-dot-to-png-in-python) reference:[Plotting the Digraph with graphviz in python from DOT file](https://stackoverflow.com/questions/41942109/plotting-the-digraph-with-graphviz-in-python-from-dot-file) reference:import[How to get pyreverse to work](https://python-forum.io/thread-27300.html) reference:[Generating UML Diagrams from Python Code](https://bhavaniravi.com/blog/generate-uml-diagrams-from-python-code/) reference:[command pyreverse help](https://helpmanual.io/help/pyreverse/) keyword:UML(from C)